Do I NEED to prime it?

If motor has been run assembly lube is long gone and motor oil does not stick around long
If motor is going to sit
change the oil and run it with STP- stp never runs off, actually embeds into the pores of the metal
and put some gas tank saver in the gas tank so your carb does not gum up- or run it dry
I've had to fix motors where the valve guides froze up with varnish after sitting- bending all the pushrods when starting

Hex stock is widely available
do not leave home without it